In-tree version of FLTK needs Fl_PNG_Image in order to use the new icon code in the viewer


git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@4920 3789f03b-4d11-0410-bbf8-ca57d06f2519
diff --git a/common/fltk/src/CMakeLists.txt b/common/fltk/src/CMakeLists.txt
index 4cb64e5..9a6d255 100644
--- a/common/fltk/src/CMakeLists.txt
+++ b/common/fltk/src/CMakeLists.txt
@@ -44,6 +44,7 @@
   Fl_Pack.cxx
   Fl_Paged_Device.cxx
   Fl_Pixmap.cxx
+  Fl_PNG_Image.cxx
   Fl_Positioner.cxx
   Fl_Printer.cxx
   Fl_Preferences.cxx